1. Field of the Invention
This invention relates to the field of radiation curable compositions, and specifically to imparting flame resistance or redardancy to such compositions and the coating, adhesives, and the like, which are the cured products of such compositions.
2. Description of the Prior Art
Radiation curable compositions are a rather recent innovation in the field of coatings and adhesives. The use of ultraviolet (UV) and electron beam (EB) technology is growing rapidly because of the low or zero volatile organic chemical emissions (VOC) obtainable through such technology, and also due to the ability to achieve high productivity. The most popular radiation curable chemistry is based on (meth)acrylates (a convention used herein to refer to both acrylates and methacrylates).
As the field of radiation curable chemistry has developed, there have been several proposals for additives to impart flame resistance, which is a serious need, especially in applications such as airplane and motor vehicle construction, electrical and electronic applications. Bromine and phosphorus-containing additives have been proposed, but so far no one has proposed a commercially acceptable additive which is compatible with the radiation curable compositions, and also reacts with the composition upon cure so as to form an integral part of the cured polymer, and which can not be extracted or otherwise rendered inactive, which is frequently the case with non-reactive bromine or phosphorus based additives. Examples of such non-reactive additives brominated dialkyl phthalate, dioctyl tetrabromophthalate, brominated styrene polymers, and brominated Bisphenol A compounds. The assignee of this application formerly produced a polymerizable fire/flame retarding material under the designation SR640, which was an ethoxylated tetrabromobisphenol A diacrylate. That material was difficult to make, and also suffered from the disadvantage of having very low solubility in typical acrylate monomers and/or oligomers used in radiation curable chemistry.
It has accordingly become an object of this invention to provide a flame retardancy additive for radiation curable compositions which is compatible and reacts with the other components of such compositions.